DRAWING ORGANIC STRUCTURESFUNCTIONAL GROUPSCONSTITUTIONAL ISOMERSDr. ClowerCHEM 2411Spring 2014
McMurry (8th ed.) sections 1.12, 3.1, 3.2
Draw these structures…• C2H6
• CH4O
• C3H6 (contains C=C)
• C4H10 (multiple possible answers)
More Lewis structures…• CH5N
• CHN
• HNO3
• Remember…• Keep in mind total available valence electrons• Try to minimize formal charges• Patterns for formal charge
Drawing Organic Structures• Example: isopropyl alcohol (C3H80)
• Lewis structure• Show all bonds, atoms, lone pairs
• Condensed structure• Omit some bonds (C─C, C─H, O─H, N─H)• Often omit lone pairs
• Skeletal structure/line-angle drawing• Show bond framework as lines• C atoms at intersections of lines (bonds) and end of each line• H atoms bonded to C are not shown• Heteroatoms (atoms other than C and H) are shown
Drawing line-angle structuresName Lewis structure Condensed structure Line-angle drawing
Acetone
Butane
1-Butene
Cyclohexane
Benzene
C C C
O H
H
H
H
H
H
C C C CH
H
H
H
H
H
H
H
H
H
C C C CH
H H H
H
H
H
H
C
CC
C
CC
HHH
H
H
H
H
H
H HH
H
H H
H
HH
H
Interpreting line-angle structures• What is the molecular formula for adrenaline?
• What is the molecular formula for thalidomide?
HO
OH
N
HO
H
N
N
O
O O
O
H
Drawing Organic Structures• Draw Lewis and line-angle structures for this condensed
structure: (CH3)3CCH2COCHCH2
Functional Groups• Collection of atoms at a
site within a molecule with a common bonding pattern
• Reacts in a typical way, generally independent of the rest of the molecule
• Four broad classes• Hydrocarbons• Compounds containing O• Compounds containing N• Compounds containing S
or P
1. Hydrocarbons• Alkane: single bonds, sp3 carbons• Cycloalkane: carbons form a ring• Alkene: double bond, sp2 carbons• Cycloalkene: double bond in ring• Alkyne: triple bond, sp carbons• Aromatic (arene): contains a benzene ring
• Not a hydrocarbon, but related…• Alkyl halide: R─X
• R = any carbon group• X = halogen
2. Compounds containing oxygen• Alcohol: R─OH• Ether: R─O─R'• Carbonyl group: C=O
• Aldehyde: RCHO
• Ketone: RCOR'
CH3CH2 C
O
H
CH3 C
O
CH3
Carboxylic acids and their derivatives• Carboxylic Acid: RCOOH
• Acid Chloride: RCOCl
• Ester: RCOOR' (RCO2R’)
• Amide: RCONH2
• Acid Anhydride: RCO2COR
C
O
OH
C
O
Cl
C
O
OCH3
C
O
NH2
CO
C
O O
3. Compounds containing nitrogen
• Amines: RNH2, RNHR', or R3N
• Amides: RCONH2, RCONHR, RCONR2
• Nitrile: RCN CH3 C N
4. Compounds containing S or P• Phosphates (PO4
2-)
• Thiol (R─SH)
• Sulfides (R─S─R)
• Sulfoxides (S=O)
• Thioester (RCOSR)
Isomers• Isomers have the same molecular formula, but different
arrangements of atoms
• Constitutional isomers • differ in their connectivity
• Stereoisomers• differ in the spatial arrangement/orientation of their atoms
Constitutional Isomers• Molecules with the same molecular formula, but different
connectivity• Same number and kinds of atoms• Differ in which atoms are bonded
• Example: C4H10
• Straight-chain (“normal”) alkane vs. branched-chain alkane
CH3 CH2 CH2 CH3 CH3 CH CH3
CH3
butane isobutane
Constitutional Isomers
Constitutional Isomers• Are the following pairs of molecules constitutional
isomers, the same molecule, or neither?
(a)
(b)
(c)
(d)
CH3 CH2 CH CH3
CH2 CH3
CH3 CH2 CH CH2 CH3
CH3
CH CH2 CH2 CH CH2
CH3
CH2
CH3 CH3CH3CH3
CH3
CH3 C
CH3
CH3
CH2 CH3 CH3 C
CH3
CH2
CH2 CH3
CH3
CH3 CH2 CH2 CH2 CH2 CH3 CH2 CH CH2
CH3 CH3 CH3
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